Navigational device

ABSTRACT

A navigation unit, especially for vehicles, with a data bus ( 3 ), with a data memory ( 2 ) on which a plurality of map information items and navigation data are stored, with a navigation computer ( 1 ), connected to the data bus ( 3 ), for route planning, with a data processing unit ( 30 ), connected to the data bus ( 3 ), for processing the data into picture information, the data processing unit ( 30 ) containing a picture memory ( 32 ) for storing the picture information, with a monitor ( 4 ), connected to the data processing unit ( 30 ), on which the picture information can be displayed, with a communication block ( 20 ) with a control unit ( 21 ) for entering the start location, intermediate destination, and/or final destination of a trip, such that the data processing unit ( 30 ) contains a map memory ( 38 ) for storing road map information.

[0001] The invention relates to a navigation unit, especially forvehicles, in accordance with the generic part of claim 1.

[0002] Known navigation units, from which the invention takes itsstarting point, are known from the prior art in a large number ofmodifications.

[0003] The main components of such a navigation unit or vehiclenavigation system are a control unit for entering the starting point,intermediate destinations, and/or final destination; a data medium fornavigation data, for example for information to display road maps; anavigation computer to plan the route and provide guidance to thedestination; a data processing unit to process the data into pictureinformation, the data processing unit generally containing a picturememory to store the picture information as well as a screen and adisplay unit to display road maps, position information, destinationinformation, etc. The individual components communicate over a data bus,which in particular can also be an optical data bus. Such navigationunits frequently also have a number of sensors to determine the vehicleposition, its speed, orientation, etc.

[0004] For example, from the U.S. Pat. No. 5,689,252 a navigation unitis known which has a microcontroller as its central unit. A data inputdevice, a GPS (=Global positioning System) signal receiver, a directionsensor, a distance sensor, and a traffic information receiver areconnected to this microcontroller. Furthermore, a data memory isconnected to it, in which is stored information about the road network,especially road maps. Data conducted from these components to themicrocontroller are made available to a navigation computer so that itcan plan the route. The data calculated in this way are then displayedon a screen, which is likewise connected to the microcomputer.

[0005] It should be noted that especially road map information cannot bedisplayed directly, but first must be transformed into pictureinformation.

[0006] Newer systems give the user the capability of freely choosing thepicture section by zoom or scroll functions. Furthermore, in suchsystems, the direction and motion of the vehicle is frequently shown onthe road maps appearing on the screen. These so-called user demands(zoom or scroll functions) and system demands (vehicle motion)continuously change the display picture information, and must becontinuously updated from suitable road map information.

[0007] The above arrangement of conventional navigation units or vehiclenavigation systems allows road map information to be retrieved by thenavigation computer individually for each displayed picture and to beput into the intermediate storage in the picture memory.

[0008] The EP 0 306 088 A1 describes a new generation navigation unit.In this navigation unit, the individual components are connected to oneanother over a data bus. Such a linkage is customary in so-called linkeddriver information systems. The advantage of such linked driverinformation systems is that a nearly arbitrary number of individualcomponents can be linked to one another over a data bus line. Forexample, a screen can be used not only to display navigation data, roadmaps, etc., but, for example, can also indicate a defect in the vehicleor the like.

[0009] The navigation unit described in the EP 0 306 088 A1 is based ona data bus, a data memory connected to this data bus, in which a largenumber of road maps and navigation data is stored; a navigation computerto plan the route, also connected to the data bus; a data processingunit, connected to the data bus, to process data into pictureinformation, said data processing unit containing a picture memory tostore the picture information; a screen, connected to the dataprocessing unit, on which the picture information can be displayed, anda communication block with a control unit for entering the startposition, intermediate destinations, and/or the final destination.

[0010] In such a system, the picture information of each road map isloaded individually into the picture memory. Such picture information isalways transferred over the bus line. If the user now wants to change,for example, the current screen display or if the motion of the vehiclecauses picture information to change continuously, transfer of road mapinformation from the data memory to the picture memory must necessarilyoccur continuously. For a screen display with sufficient picture refreshcycles, the data bus must therefore have a large bandwidth, whichgenerally is not available. Furthermore, the data bus is needed almostexclusively for transferring picture information, so that otherinformation or data cannot be transferred or can be transferred onlyserially during the remaining interim times.

[0011] To elucidate this, the above restrictions will be explained interms of two examples:

[0012] In a first generation navigation unit, as shown in FIG. 1, thecentral unit is a navigation computer 1. External information isconducted to this navigation computer 1. In this example, the navigationcomputer obtains this information from a sensor block 10, a data memory2, and a communication block 20.

[0013] In this example, the sensor block 10 contains a direction sensor12 and a position sensor 13. The data memory 2 stores information aboutroad networks. This includes in particular information for displayingroad maps, information about road signs, information about speed limitson the roads, and other navigation data. This data memory 2 generally isa CD-ROM, but any other storage medium is also conceivable. The datastored in the data memory 2 require updating at longer time intervals;in this example, the communication block 20 has the purpose ofconducting to the navigation computer 1 navigation data which areconstantly changing. Thus, this communication block 20 contains acontrol unit 21 for entering the destination and setting the screenfunctions, especially for selecting a road map section (zoom and/orscroll functions). Furthermore, a traffic data receiver 22 is alsoassociated with this communication block 20. For example, this receivercan receive current traffic information from various radio stations, andcan process this information appropriately.

[0014] The data that are conducted or can be conducted from theseindividual components 10, 2, and 20 to the navigation computer 1 areused by the navigation computer 1 to plan a route and to guide thedriver to his destination. The road map display calculated in this wayshould then be conducted to a screen 4. Such road map information,created by the navigation computer 1, cannot be displayed directly,however, but must be converted into picture information by a suitabletransformation.

[0015] In present navigation systems or navigation units, a dataprocessing unit 30 for this purpose is usually directly associated withthe navigation computer 1.

[0016] In the example of FIG. 1, the transformation of road mapinformation and the picture information, which is performed in the dataprocessing unit 30, is accomplished by means of a transformation unit 31provided for this purpose. The road map information, which has beenconverted into picture information by means of the transformation unit31, is then interim stored in the picture memory 32 and subsequently isdisplayed on the screen 4.

[0017] The data furnished by the sensor block 10 are needed not only bythe navigation computer 1 for route planning and destination guidance,but such vehicle navigation systems or navigation units should also showthe motions of the vehicle on the screen 4. Furthermore, such navigationunits usually make it possible for the user himself to select a road mapsection for viewing. For this purpose, the user is able, for example, toimplement zoom and/or scroll functions. Such user requests areidentified by the reference symbol B. Requests which are transmitteddirectly from the vehicle and on the basis of which the pictureinformation changes are identified in this example as system requests S.Such a system request S preferably is issued on the basis of the datathat are made available from the sensor block 10. In the drawing, forthe sake of clarity these system requests S and user requests B areconducted to the navigation computer 1 on the request line 6.

[0018]FIG. 1 shows the arrangement of a first generation vehiclenavigation system or navigation unit. In such a system, extensivestorage of road map information in the data processing unit 30 can bedispensed with. Storing the picture information in the picture memory 32is sufficient since the road map information for each picture can befurnished individually by the navigation computer 1 of the dataprocessing unit, by accessing the data memory 2 as necessary.

[0019] The data processing unit 30 is not able to process user requestsB and/or system requests S and to generate new picture information fromthis.

[0020] In a second generation of navigation systems, the navigation unititself is integrated into a complex driver information system. Such adriver information system is intended to transmit current data to thedriver, for example about the state of his vehicle, malfunctions, etc.The individual components of such a driver information system are, forexample, sensors, input devices, radio receivers, amplifiers,loudspeakers, display devices, monitors, etc. They are linked with oneanother through a common, standardized bus.

[0021]FIG. 2 shows how the individual components of such a navigationunit are integrated into such a driver information system. Inparticular, FIG. 2 shows how such a navigation unit, in accordance withthe EP 0 306 088, can be realized with the individual components fromFIG. 1, by means of a bus structure.

[0022] A navigation computer 1, a data memory 2, a control unit 39, anda sensor block 10 are connected to a data bus 3. A communication block20 and a transformation unit 31 are likewise connected. Thetransformation unit 31 is connected to a picture memory 32, and thepicture memory 32 again is connected to a screen 4.

[0023] The components 20 and 31 are designed as standard modules, andconsequently can be actuated not only by the navigation system ornavigation unit itself but also by other devices connected thereto. Theseparation of the navigation computer 1′ and the screen 4, which isconnected to the data bus 3 via the transformation unit 31 and thepicture memory 32, has a result that, due to the limited bandwidth ofthe data bus line 3 and the need for transmission between othercomponents connected to the data bus 3, the picture on the screen 4 canbe renewed only at relatively long time intervals. System requests Sand/or user requests B, as indicated in FIG. 1, thus can generally notbe processed at all or else their discontinuous picture display cannotbe assured.

[0024] It is therefore the object of the invention to present anavigation unit which is suited for networked driver informationsystems, and in which road map information can be transmitted from thenavigation computer to the data processing unit and thus to the screenin such a way that, even with a limited bandwidth of the data bus, anadequate picture refresh rate is still possible.

[0025] The invention accomplishes this object by a navigation unit withthe characteristic features of claim 1.

[0026] Advantageous modifications and developments of the invention arespecified in the subclaims.

[0027] The essential idea of the invention is that the data processingunit itself has a road map memory for storing road map information. Thisroad map memory puts into intermediate storage the information that hasalready been transmitted by the navigation computer. This information islocally available in the data processing unit and is available forscreen display as needed, without communication with the navigationcomputer being necessary. This means that the information in the dataprocessing unit is used not only once but several times, which reducesthe load on the bus. Not until picture information which exists only inthe data memory connected to the data bus needs to be displayed, isaccess to the navigation computer and thus to the data bus necessary,since the latter responds by transmitting the needed information. Thisnewly-transmitted information displaces the outmoded and no longernecessary information, as needed, from the road map memory of the dataprocessing unit. Direct access of the data processing unit to the datamemory is counterproductive due to the software modularity of thenavigation computer.

[0028] However, in general, modularization facilitates expansion orreplacement of individual components. For this reason, modularizationcannot be dispensed with. The invention achieves a maximum offlexibility in this regard in that the navigation computer and the dataprocessing unit are designed as modules, which are implemented with twoseparate microprocessors.

[0029] Since the vehicle usually moves continuously, suitable datamanagement in the data processing unit makes it possible to detectalready at an early stage which road map information will be neededsubsequently due to the vehicle motion. This information can already berequested prospectively from the navigation computer (look-aheadprinciple), so that more time is available for its transmission. Thisreduces the bandwidth need for the data bus even further and thuscorrespondingly relieves the network.

[0030] In an especially advantageous modification of the invention, thedata bus is designed as a “Media-Oriented Synchronous Transfer”—(MOST)or as a “Multi-Media Link” (MML) bus. In combination with theabove-mentioned modular structure, such standardized buses guaranteethat the inventive navigation system can easily be integrated intonearly all current vehicle brands.

[0031] In an advantageous modification of the invention, thecommunication block has a control unit for inputting a user request tochange the current picture information, and a traffic data receiver forreceiving current traffic information. It makes no difference whetherthis information is conducted directly to the navigation computer or viathe data bus. The control unit for inputting user requests can also beassociated with the data processing unit, for example, if input is made,for example, through a touch-screen.

[0032] Furthermore, the invention specifies that a sensor block foracquiring position data is associated with the navigation computer. Foracquiring position data, a position sensor, for example, can detect theinstantaneous actual position and/or a direction sensor can detect theinstantaneous orientation of the vehicle. A speedometer and/ortachometer can also be present.

[0033] It is anticipated that the position data detected by the sensorblock will contain a system request for changing the current pictureinformation. The user request entered into the control unit and/or thesystem request made available, for example, by the sensor block, areconducted to the data processing unit. The latter suitably transforms aroad map from the map memory into picture information or requestsfurther map information from the navigation computer.

[0034] The drawing shows an embodiment of the invention, which will bedescribed in more detail below.

[0035]FIG. 1 shows an arrangement of a navigation unit of the firstgeneration without a data bus, according to the prior art.

[0036]FIG. 2 shows a navigation unit of the second generation with adata bus according to the prior art.

[0037]FIG. 3 shows an embodiment of an inventive navigation unit.

[0038]FIG. 4 shows a flowchart to demonstrate the management andprocessing of the road maps stored in the map memory of the dataprocessing unit.

[0039]FIG. 3 shows, by way of example, how a navigation unit is realizedin an inventive data bus structure. A navigation computer 1, a datamemory 2, and a data processing unit 30 are connected to a data bus 3.In the example, other components connected to the data bus arecharacterized by a single block symbol and designated by the referencesymbol 7.

[0040] As in the first generation navigation unit of FIG. 1, data areconducted to the navigation computer 1. Here, too, for example aspeedometer 11, a direction sensor 12, a position sensor 13, and atachometer 14 have been sketched. Furthermore, analog information isconducted to the navigation computer 1 from the communication block 20,especially from the control unit 21, and the traffic data receiver 22.Of course, this information from the communication block 20 and thesensor block 10 can be transmitted over the data bus 3.

[0041] Otherwise than with the first generation navigation unit of FIG.1, the user requests B and system requests S, which in this example aretransmitted from the control unit 21 or the sensor block 10, are notconducted to the navigation computer 1 but over the request line 6 ofthe data processing unit 30.

[0042] Therefore, while in a traditional navigation system, the newrequests S and B are processed by the navigation computer 1, theinvention specifies that a new request S/B is processed essentiallylocally in the data processing unit 30. The invention thereforespecifies that a control unit 31 precedes the standard units, namely themonitor 4, the picture memory 32, and the transformation unit 31. Thiscontrol unit 39 receives the user requests B and the system requests Svia the request line 6. The map memory 38 is connected to this controlunit 39. The map memory can store larger quantities of road mapinformation that is conducted from the data memory 2 via the data bus 3to the navigation computer 1. The control unit 39 itself is for thispurpose connected to the data bus 3 through a network adapter 37.

[0043] A variant of this design is that the data memory 2 is notconnected to the data bus 3 but to the navigation computer 1.

[0044] According to the invention, the data processing unit 30 isdesigned in such a way that user requests B and system requests S can beprocessed independent of the navigation computer 1, i.e. locally. Newmap information is requested actively from the navigation computer 1only as needed, according to the client-server principle. The map memory38, which is situated next to the picture memory 32 in the dataprocessing unit 30, is able to carry in intermediate storage the mapinformation transmitted from the navigation computer 1.

[0045] Under the assumption that user requests B and system requests Scan largely be processed with locally available map information in themap memory 38 (cache principle), the current screen content can becalculated from the map memory 38 without communicating with thenavigation computer 1. This means that the map information in the dataprocessing unit 30 is used not only once but several times, thusreducing the bus load. Due to reduced inquiries of the data processingunit 30, the navigation computer 1 is able to supply several dataprocessing units 30, 30 a, 30 b with data. This makes it possible todisplay different map sections on several independent screens 4, 4 a, 4b, e.g. the current environment and the environment of the destination.

[0046] Only if the user—or system requests B, S—require access to mapinformation which is not available in the map memory 38 of the dataprocessing unit 30, must map information be requested from thenavigation computer 1. The latter responds by transmitting the necessarymap information. Newly transmitted map information replaces outmoded andno longer needed map information from the map memory 38 of the dataprocessing unit 30, as appropriate.

[0047] Since the vehicle usually moves continuously, suitablecalculations and control operations of the control unit 39 make itpossible to detect already at an early stage what map information willbe needed subsequently on the basis of the system requests S. Such mapinformation thus can already be requested from the navigation computer 1prospectively and can be conducted to the map memory 38. Consequently,more time is available for this transmission. This again reduces thebandwidth needed for the data bus 3 and correspondingly relieves theentire network.

[0048] The flowchart in FIG. 4 shows how such a request for new mapinformation can be requested by the data processing unit 30 from thenavigation computer 1.

[0049] When (a) a new request (user request B and/or system request S)occurs, a test is first made whether a new picture is needed at all (b).

[0050] For example, if the new vehicle position and/or orientationdiffers only slightly from the current one, it is unnecessary tocalculate a new picture if the display scale is sufficiently large,since the differences in any case would not be visible within theframework of the given resolution. In this case, processing of the newrequest terminates (c).

[0051] If the differences are sufficiently large to require a newpicture, the control unit 39 first must test whether the map informationneeded to calculate the new picture information is present in the mapmemory 38 (d). This situation can occur e.g. due to previous requests B,S. If this is the case, the new picture information can be calculatedimmediately, stored in the picture memory 32, and displayed on thescreen 4 or on the display (i). In this case, processing of the newrequests B, S is completed (c).

[0052] If the new map information must first be loaded, the needed mapinformation (e) is requested via the data bus from the navigationcomputer 1. The latter sends the requested map information via the databus 3 to the data processing unit 30. Since the map information usuallyis available in whole pages, whole pages are also transmitted.

[0053] The map information is received by the network adapter 37 in thedata processing unit 30 (f), and is inserted by the control unit 39 inthe map memory 38 for later accesses (g). The excessive map informationthat has initially been transmitted due to the page partitioning, isthen available immediately in case of further continuous system requestsS (look-ahead principle).

[0054] Now all map information needed due to the requests B, S (a) ispresent in the map memory 28. The new map information can then becalculated in the transformation unit 31, stored in the picture memory32, and outputted on the screen 4 (h).

[0055] Processing of the request is thus completed (i).

List of Reference Symbols

[0056]1 Navigation computer

[0057]2 Data memory

[0058]3 First data bus

[0059]4, 4 a, 4 b Screen

[0060]6 Request line

[0061]7 Other components

[0062]10 Sensor block

[0063]11 Speedometer

[0064]12 Direction sensor

[0065]13 Position sensor

[0066]14 Tachometer

[0067]20 Communication block

[0068]21 Control unit

[0069]22 Traffic data receiver

[0070]30, 30 a, 30 b Data processing unit

[0071]31 Transformation unit

[0072]32 Picture memory

[0073]37 Network adapter

[0074]38 Map memory

[0075]39 Control unit

[0076] B User request

[0077] S System request

1. A navigation unit, especially for vehicles, (a) with a data bus (3),(b) with a data memory (2) on which a plurality of map information itemsand navigation data are stored, (c) with a navigation computer (1),connected to the data bus (3), for route planning, (d) with a dataprocessing unit (30), connected to the data bus (3), for processing thedata into picture information, the data processing unit (30) containinga picture memory (32) for storing the picture information, (e) with amonitor (4), connected to the data processing unit (30), on which thepicture information can be displayed, (f) with a communication block(20) with a control unit (21) for entering the start location,intermediate destination, and/or final destination of a trip,characterized in that the data processing unit (30) contains a mapmemory (38) for storing road map information.
 2. The navigation unit ofclaim 1, characterized in that the data processing unit (30) contains acontrol unit (39) for prospectively requesting map information.
 3. Thenavigation unit of one of the preceding claims, characterized in thatthe communication block (20) contains a control unit (21) for entering auser request (B) to change the current picture information.
 4. Thenavigation unit of one of the preceding claims, characterized in thatthe communication block (20) contains a traffic data receiver (22) toreceive current traffic information.
 5. The navigation unit of one ofthe preceding claims, characterized in that the sensor block (10) toacquire position data is associated with the navigation computer (1). 6.The navigation unit of claim 5, characterized in that the sensor block(10) for acquiring position data has a position sensor (13) to acquirethe actual instantaneous position.
 7. The navigation unit of one of theclaims 5 or 6, characterized in that, in order to acquire position data,the sensor block (10) has a direction sensor (12) to acquire theinstantaneous orientation of the vehicle and/or a speedometer (11)and/or a tachometer (14).
 8. The navigation unit of one of the claims 5to 7, characterized in that the position data acquired by the sensorblock (10) effect a system request (S) directly in the data processingunit (30), which results in changing the current picture information. 9.The navigation unit of one of the preceding claims, characterized inthat the data processing unit (30) has a control unit (39) to manage andprocess the road maps stored in the map memory (30).
 10. The navigationunit of claim 9, characterized in that the control unit (39) is actuatedby a user request (B) and/or a system request (S) to manage and processthe road data stored in the map memory (38).
 11. The navigation unit ofone of the preceding claims, characterized in that the data bus (3) isan MOST bus or an MML bus.
 12. The navigation unit of one of thepreceding claims, characterized in that the navigation computer (1) andthe data processing unit (30) are implemented with two separate μprocessors.
 13. The navigation unit of one of the preceding claims,characterized in that two or more independent data processing units (30,30 a, 30 b) and monitors (4, 4 a, 4 b) display independent map sections.